Single Energy Source Projectile Perforating System

ABSTRACT

A method and apparatus for perforating a wellbore by firing one or more projectiles into a casing and formation using a single source of energy.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 63/122,872, filed Dec. 8, 2020.

BACKGROUND OF THE INVENTION

Generally, when completing a subterranean well for the production of fluids, minerals, or gases from underground reservoirs, several types of tubulars are placed downhole as part of the drilling, exploration, and completions process. These tubulars can include casing, tubing, pipes, liners, and devices conveyed downhole by tubulars of various types. Each well is unique, so combinations of different tubulars may be lowered into a well for a multitude of purposes.

A subsurface or subterranean well transits one or more formations. The formation is a body of rock or strata that contains one or more compositions. The formation is treated as a continuous body. Within the formation hydrocarbon deposits may exist. Typically a wellbore will be drilled from a surface location, placing a hole into a formation of interest. Completion equipment will be put into place, including casing, tubing, and other downhole equipment as needed. Perforating the casing and the formation with a perforating gun is a well-known method in the art for accessing hydrocarbon deposits within a formation from a wellbore.

Explosively perforating the formation using a shaped charge is a widely known method for completing an oil well. A shaped charge is a term of art for a device that when detonated generates a focused output, high energy output, and/or high velocity jet. This is achieved in part by the geometry of the explosive in conjunction with an adjacent liner. Generally, a shaped charge includes a metal case that contains an explosive material with a concave shape, which has a thin metal liner on the inner surface. Many materials are used for the liner; some of the more common metals include brass, copper, tungsten, and lead. When the explosive detonates, the liner metal is compressed into a super-heated, super pressurized jet that can penetrate metal, concrete, and rock. Perforating charges are typically used in groups. These groups of perforating charges are typically held together in an assembly called a perforating gun. Perforating guns come in many styles, such as strip guns, capsule guns, port plug guns, and expendable hollow carrier guns.

Perforating charges are typically detonated by a detonating cord in proximity to a priming hole at the apex of each charge case. Typically, the detonating cord terminates proximate to the ends of the perforating gun. In this arrangement, an initiator at one end of the perforating gun can detonate all of the perforating charges in the gun and continue a ballistic transfer to the opposite end of the gun. In this fashion, numerous perforating guns can be connected end to end with a single initiator detonating all of them.

The detonating cord is typically detonated by an initiator triggered by a firing head. The firing head can be actuated in many ways, including but not limited to electronically, hydraulically, and mechanically.

Expendable hollow carrier perforating guns are typically manufactured from standard sizes of steel pipe with a box end having internal/female threads at each end. Pin ended adapters, or subs, having male/external threads are threaded one or both ends of the gun. These subs can connect perforating guns together, connect perforating guns to other tools such as setting tools and collar locators, and connect firing heads to perforating guns. Subs often house electronic, mechanical, or ballistic components used to activate or otherwise control perforating guns and other components.

Perforating guns typically have a cylindrical gun body and a charge tube, or loading tube that holds the perforating charges. The gun body typically is composed of metal and is cylindrical in shape. Charge tubes can be formed as tubes, strips, or chains. The charge tubes will contain cutouts called charge holes to house the shaped charges.

It is generally preferable to reduce the total length of any tools to be introduced into a wellbore. Among other potential benefits, reduced tool length reduces the length of the lubricator necessary to introduce the tools into a wellbore under pressure. Additionally, reduced tool length is also desirable to accommodate turns in a highly deviated or horizontal well. It is also generally preferable to reduce the tool assembly that must be performed at the well site because the well site is often a harsh environment with numerous distractions and demands on the workers on site.

Electric initiators are commonly used in the oil and gas industry for initiating different energetic devices down hole. Most commonly, 50-ohm resistor initiators are used. Other initiators and electronic switch configurations are common.

Modular or “plug and play” perforating gun systems have become increasingly popular in recent years due to the ease of assembly, efficiencies gained, and reduced human error. Most of the existing plug and play systems either (1) utilize a wired in switch and/or detonator, or (2) require an initiating “cartridge” that houses the detonator, switch, electrical contacts and possibly a pressure bulkhead. The wired in switch/detonator option is less desirable, because the gun assembler must make wire connections which is prone to human error. The initiating cartridge option is less desirable because the cartridge can be a large explosive device—in comparison to a standard detonator—thus takes up additional magazine space at the user facility. There is a need for a modular perforating system in which no wire connections are required by the user AND the switch and pressure bulkhead are in pre-assembled in the gun assembly rather than in the initiating cartridge. The detonator for the proposed system has no wires and allows for simple arming by the user in the field.

SUMMARY OF EXAMPLE EMBODIMENTS

An example embodiment may include a perforating gun system comprising a cylindrical housing with a center axis, an outer surface, an internal pressure chamber, a cylindrical thru hole extending axially from the internal pressure chamber and terminating at a first end of the cylindrical housing, an energy source disposed within the pressure chamber, a plurality of cylindrical ports extending radially from the thru hole to the outer surface of the cylindrical housing, a plurality of projectiles, one each disposed in each of the plurality of cylindrical ports, a plurality of pressure seals, one each disposed in each of the plurality of cylindrical ports, and an end cap pressure seal capping off the end of the cylindrical thru hole where it terminates at the first end, wherein energy source generates a gas at a pressure sufficient to propel the plurality of projectiles through the pressure seals and into a casing surrounding the perforating gun system.

A variation of the example embodiment may include each of the plurality of cylindrical ports extending tangentially to the center axis of the cylindrical housing. Each of the plurality of cylindrical ports may extend at a non-normal angle to the center axis of the cylindrical housing. Each of the plurality of cylindrical ports may extend non-linearly from the center axis of the cylindrical housing. The plurality of cylindrical ports may have a phase angle between each cylindrical port about the center axis of the cylindrical housing. The plurality of cylindrical ports may be in a single phase. The plurality of cylindrical ports may be in a single plane. The plurality of cylindrical ports may be in a plurality of planes. The cylindrical housing may be a first cylindrical housing, containing the pressure chamber, coupled to a second cylindrical housing containing the plurality of cylindrical ports. The first cylindrical housing may have a pin end that engages into a box end of the second cylindrical housing. The first cylindrical housing may have an inner cavity that engages into a plug end of the second cylindrical housing.

An example embodiment may include a perforating gun system comprising a first cylindrical housing with an outer surface, an internal pressure chamber, a cylindrical thru hole extending axially from the internal pressure chamber and terminating at a first end of the first cylindrical housing, a second cylindrical housing coupled in series with the first cylindrical housing, having an outer surface, a cylindrical thru hole, and a plurality of cylindrical ports extending radially from the thru hole to the outer surface of the second cylindrical housing, wherein both first cylindrical housing and second cylindrical housing share a common center axis, an energy source disposed within the pressure chamber, a plurality of projectiles, one each disposed in each of the plurality of cylindrical ports, a plurality of pressure seals, one each disposed in each of the plurality of cylindrical ports, and an end cap pressure seal capping off the end of the cylindrical thru hole where it terminates at an end of the second cylindrical housing, wherein energy source generates a gas at a pressure sufficient to propel the plurality of projectiles through the pressure seals and into a casing surrounding the perforating gun system.

A variation of the example embodiment may include each of the plurality of cylindrical ports extending tangentially to the center axis of the second cylindrical housing. Each of the plurality of cylindrical ports may extend at a non-normal angle to the center axis of the second cylindrical housing. Each of the plurality of cylindrical ports may extend non-linearly from the center axis of the second cylindrical housing. The plurality of cylindrical ports may have a phase angle between each cylindrical port about the center axis of the second cylindrical housing. The plurality of cylindrical ports may be in a single phase. The plurality of cylindrical ports may be in a single plane. The plurality of cylindrical ports may be in a plurality of planes. It may include the first cylindrical housing having a pin end that engages into a box end of the second cylindrical housing. It may include the first cylindrical housing having an inner cavity that engages into a plug end of the second cylindrical housing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings in which reference numbers designate like or similar elements throughout the several figures of the drawing. Briefly:

FIG. 1 shows an example embodiment with multiple projectiles energized by a single non-touching source.

FIG. 2 shows an example embodiment where the source can be multiple geometry configurations, including conforming to a random path.

FIG. 3 shows an example embodiment with a non-centered pathway.

FIG. 4 shows an example embodiment with a non-linear pathway.

FIG. 5 shows an example embodiment with external pressure seals.

FIG. 6 shows an example embodiment with internal pressure seals.

FIG. 7 shows an example embodiment with open ports.

FIG. 8 shows an example embodiment with a stackable multiple piece projectile chamber.

FIG. 9 shows an example embodiment with a multiple piece projectile chamber.

FIG. 10 shows an example embodiment with multiple perforating planes.

FIG. 11 shows an example embodiment with a single perforating plane.

FIG. 12 shows an example embodiment with multiple phases for the perforation projectiles.

FIG. 13 shows an example embodiment with a single phase for the perforation projectiles.

FIG. 14 shows an example embodiment with an angled, or non-perpendicular, projectile direction with respect to the axis of the bore.

FIG. 15 shows an example embodiment with non-linear or curved projective paths from the chamber to the exit.

DETAILED DESCRIPTION OF EXAMPLES OF THE INVENTION

In the following description, certain terms have been used for brevity, clarity, and examples. No unnecessary limitations are to be implied therefrom and such terms are used for descriptive purposes only and are intended to be broadly construed. The different apparatus, systems and method steps described herein may be used alone or in combination with other apparatus, systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.

Terms such as booster may include a small metal tube containing secondary high explosives that are crimped onto the end of detonating cord. The explosive component is designed to provide reliable detonation transfer between perforating guns or other explosive devices, and often serves as an auxiliary explosive charge to ensure detonation.

Detonating cord is a cord containing high-explosive material sheathed in a flexible outer case, which is used to connect the detonator to the main high explosive, such as a shaped charge. This provides an extremely rapid initiation sequence that can be used to fire several shaped charges simultaneously.

A detonator or initiation device may include a device containing primary high-explosive material that is used to initiate an explosive sequence, including one or more shaped charges. Two common types may include electrical detonators and percussion detonators. Detonators may be referred to as initiators. Electrical detonators have a fuse material that burns when high voltage is applied to initiate the primary high explosive. Percussion detonators contain abrasive grit and primary high explosive in a sealed container that is activated by a firing pin. The impact of the firing pin is sufficient to initiate the ballistic sequence that is then transmitted to the detonating cord.

The example embodiments disclose a method for perforating casing using single or multiple projectiles that are energized by a single non-touching source that is located in a shared gas\pressure chamber. When initiated, the source creates pressure. Due to the large size of the pressure source and the small size of the open chamber, the pressure builds to high levels quickly, but non-instantaneously. The pressure is transferred down a path. The pressure is applied to the back of single/multiple tight fitting projectiles. As the projectiles move down chambers in the tool, they increase in velocity. When enough pressure is achieved, the projectiles are propelled out of the tool where they perforate through a string of casing.

The example embodiments disclose a method for perforating casing using multiple projectiles that are energized by a single source: a shared gas\pressure chamber. The example embodiments disclose a method for perforating casing using a single or multiple projectile(s) energized by a non-touching source.

The source can be either pyrotechnic or high explosive. The source can be liquid, solid, gas, or a granular substance. The source can be an instantaneous release of pressure or slow building in pressure. The source can be composed of multiple compositions. The source can be any geometry, including cylindrical or conforming to a random path.

The tool containing the projectiles can have a centered, de-centered, or non-linear bore, such as in FIGS. 3 and 4 . It can have non-linear pressure paths, as seen in FIGS. 3 and 4 . It can have internal or external pressure-sealed or open to well-bore fluid as seen in FIGS. 5-7 . It can be a single or multiple use tool. It can have stackable units to add more shots as seen in FIGS. 8-9 . It can be filled with fluid, foam, or gel. It can have pre-existing internal pressure. It can have pressure rupture membranes. It can have a multiple piece projectile chamber as shown in FIGS. 8-9 . It can have a smooth/bored/slotted paths/chamber in which the projectiles travel. It can have non-linear or curved projectile paths/chambers as shown in FIG. 15 . It can have open or closed ends. It can have the pressure act on a separate object that would then act on the bullets.

The configuration of the projectiles can be on a single plane or multiple planes as shown in FIGS. 10-11 . It can be single phased or multiple phased as shown in FIGS. 12-13 . It can be angled (not on a right angle or normal to the gun or its center axis) as shown in FIG. 14 .

The projectiles can be solid, powdered, or frangible. The projectiles can be metal, ceramic, composite, or plastic. The projectiles can have an outer shell. The projectiles can be round, square, rectangular, or angled. The projectiles can be in a cartridge with other material. The projectiles can be pre-assembled. The projectiles can have multiple projectiles per chamber. The projectiles can be fixed in location or floating. The projectiles can be pre-loaded or loaded by customer. The projectiles can be held in place by magnets. The projectiles can be dissolvable.

FIG. 1 shows an example embodiment with multiple projectiles energized by a single non-touching source. A perforating gun 10 in this example is located within a well casing 11. The perforating gun 10 has a top sub 15 with a cylindrical opening forming a pressure chamber 17 containing an energy source 16 for generating pressurized gas. The top sub 15 has a pin end 20. The top sub 15 has a center axis 50. A gas pathway 18 provides communication between the pressure chamber 17 and a plurality of ports 19. Each projectile opening 19 includes a projectile 12 and a pressure seal 13. A further pressure seal 14 seals the end of the pathway 18. Igniting or otherwise activating the release of energy in the form of pressurized gas from the energy source 16 builds up pressure in the pressure chamber 17, which pressurizes the pathway 18, and thus pressurizes against the projectiles 12 located within the ports 19. The pressure continues to build until the pressure seals 13 give way, allowing the projectiles 12 to exit the ports 19 with sufficient energy to perforate the casing 11 and beyond to a desired distance inside the formation behind the casing 11.

FIG. 2 shows an example embodiment where the source can be multiple geometry configurations, including conforming to a random path. A perforating gun 10 in this example is located within a well casing 11. The perforating gun 10 has a top sub 15 with a cylindrical opening forming a pressure chamber 17 containing an energy source 16 a-d, providing different examples of the different configuration for the energy source, for generating pressurized gas. A gas pathway 18 provides communication between the pressure chamber 17 and a plurality of ports 19. Each projectile opening 19 includes a projectile 12 and a pressure seal 13. A further pressure seal 14 seals the end of the pathway 18. Igniting or otherwise activating the release of energy in the form of pressurized gas from the energy source 16 a-d builds up pressure in the pressure chamber 17, which pressurizes the pathway 18, and thus pressurizes against the projectiles 12 located within the ports 19. The pressure continues to build until the pressure seals 13 give way, allowing the projectiles 12 to exit the ports 19 with sufficient energy to perforate the casing 11 and beyond to a desired distance inside the formation behind the casing 11.

FIG. 3 shows an example embodiment with a non-centered pathway 18.

FIG. 4 shows an example embodiment with a non-linear pathway 18 and no pressure seal for the end of the pathway 18.

FIG. 5 shows an example embodiment with external pressure seals 13, whereas FIG. 6 shows an example embodiment with internal pressure seals 13. In this example embodiment the pressure builds against the internal pressure seals 13 until a critical pressure where the pressure seals 13 fail, thus subjecting the projectiles 12 to an explosive amount of pressure capable causing the projectiles 12 to penetrate the casing 11 and beyond into the formation.

FIG. 7 shows an example embodiment with open ports 19. In this configuration pressure builds in the pressure chamber 17 until a critical pressure is reached to overcome the internally located pressure seal 14. There are no individual pressure seals for each port 19. Once the pressure overcomes the pressure seal 14 the explosive pressure then propels the projectiles 12 into the casing 11 and beyond.

FIG. 8 shows an example embodiment with a stackable multiple piece projectile chamber. In this example there is a first sub 21 with a pin end 23 that couples into the box end 24 of a second sub 22. The second sub 22 has a pin end 25. The pathway 18 travels through both the first sub 21 and the second sub 22, where it terminates with a pressure seal 14. In this example, there are ports 19 in both the first sub 21 and the second sub 22, however, there could be configurations where the ports are all in the first sub 21 or the second sub 22.

FIG. 9 shows an example embodiment with a multiple piece projectile chamber. In this example there is a first sub 30 and a second sub 31. First sub 30 has an inner cavity 32 that accepts the plug end 33 from second sub 31. Second sub 31 has an end cap 34. In this example, the pathway 18 travels through both the first sub 30 and into the second sub 31, where it terminates against the cap 34. Second sub 31 could be more than one piece, such as the plug portion being a first piece and the end cap being a second piece. The ports 19 traverse through both the first sub 30 and the second sub 31. In this example the pressure seals 13 are located in the first sub 30 while the projectiles 12 are located in the second sub 31.

FIG. 10 shows an example embodiment with multiple perforating planes. In this example, the projectiles 12 and ports 19 are aligned within a first plane 41 or a second plane 42. This depicts a plurality of planes and there could be more planes than the two shown.

FIG. 11 shows an example embodiment with a single perforating plane. In this example, the projectiles 12 and ports 19 are aligned within a first plane 41.

FIG. 12 shows an example embodiment where the projectiles 12 and ports 19 are aligned to provide perforations in multiple phases.

FIG. 13 shows an example embodiment where the projectiles 12 and ports 19 are aligned to provide perforations in a single phase.

FIG. 14 shows an example embodiment where the projectiles 12 and ports 19 are angled, or non-perpendicular to the center axis of the top sub 15, allowing the projectile 12 perforation direction to perforate in a direction that is not normal to the center axis of the top sub.

FIG. 15 shows an example embodiment with non-linear paths 50 and 51, or curved projective paths, from the chamber to the exit, resulting in the projectiles 12 traveling along a non-linear pathway prior to exiting the top sub 15. This could be desirable in situations where diameter constraints preclude a more traditional perpendicular port. For example, the projectile 12 could be accelerated along the length of the top sub 15 first, and then curved to exit the tool and perforate the casing 11.

Initiators may be used to initiate a perforating gun, a cutter, a setting tool, or other downhole energetic device. For example, a cutter is used to cut tubulars with focused energy. A setting tool uses a pyrotechnic to develop gases to perform work in downhole tools. Any downhole device that uses an initiator may be adapted to use the modular initiator assembly disclosed herein.

Although the invention has been described in terms of embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto. For example, terms such as upper and lower or top and bottom can be substituted with uphole and downhole, respectfully. Top and bottom could be left and right, respectively. Uphole and downhole could be shown in figures as left and right, respectively, or top and bottom, respectively. Generally downhole tools initially enter the borehole in a vertical orientation, but since some boreholes end up horizontal, the orientation of the tool may change. In that case downhole, lower, or bottom is generally a component in the tool string that enters the borehole before a component referred to as uphole, upper, or top, relatively speaking. The first housing and second housing may be top housing and bottom housing, respectfully. In a gun string such as described herein, the first gun may be the uphole gun or the downhole gun, same for the second gun, and the uphole or downhole references can be swapped as they are merely used to describe the location relationship of the various components. Terms like wellbore, borehole, well, bore, oil well, and other alternatives may be used synonymously. Terms like tool string, tool, perforating gun string, gun string, or downhole tools, and other alternatives may be used synonymously. The alternative embodiments and operating techniques will become apparent to those of ordinary skill in the art in view of the present disclosure. Accordingly, modifications of the invention are contemplated which may be made without departing from the spirit of the claimed invention. 

What is claimed is:
 1. A perforating gun system comprising: a cylindrical housing with an outer surface, a center axis, an internal pressure chamber, a cylindrical thru hole extending axially from the internal pressure chamber and terminating at a first end of the cylindrical housing; an energy source disposed within the pressure chamber; a plurality of cylindrical ports extending radially from the thru hole to the outer surface of the cylindrical housing; a plurality of projectiles, one each disposed in each of the plurality of cylindrical ports; a plurality of pressure seals, one each disposed in each of the plurality of cylindrical ports; and an end cap pressure seal capping off the end of the cylindrical thru hole where it terminates at the first end, wherein energy source generates a gas at a pressure sufficient to propel the plurality of projectiles through the pressure seals and into a casing surrounding the perforating gun system.
 2. The perforating gun system of claim 1 wherein each of the plurality of cylindrical ports extend tangentially to the center axis of the cylindrical housing.
 3. The perforating gun system of claim 1 wherein each of the plurality of cylindrical ports extend at a non-normal angle to the center axis of the cylindrical housing.
 4. The perforating gun system of claim 1 wherein each of the plurality of cylindrical ports extend non-linearly from the center axis of the cylindrical housing.
 5. The perforating gun system of claim 1 wherein the plurality of cylindrical ports has a phase angle between each cylindrical port about the center axis of the cylindrical housing.
 6. The perforating gun system of claim 1 wherein the plurality of cylindrical ports are in a single phase.
 7. The perforating gun system of claim 1 wherein the plurality of cylindrical ports are in a single plane.
 8. The perforating gun system of claim 1 wherein the plurality of cylindrical ports are in a plurality of planes.
 9. The perforating gun system of claim 1 wherein the cylindrical housing is a first cylindrical housing, containing the pressure chamber, coupled to a second cylindrical housing containing the plurality of cylindrical ports.
 10. The perforating gun system of claim 9 further comprising the first cylindrical housing has a pin end that engages into a box end of the second cylindrical housing.
 11. A perforating gun system comprising: a first cylindrical housing with an outer surface, an internal pressure chamber, a cylindrical thru hole extending axially from the internal pressure chamber and terminating at a first end of the first cylindrical housing; a second cylindrical housing coupled in series with the first cylindrical housing, having an outer surface, a cylindrical thru hole, and a plurality of cylindrical ports extending radially from the thru hole to the outer surface of the second cylindrical housing, wherein both first cylindrical housing and second cylindrical housing share a common center axis; an energy source disposed within the pressure chamber; a plurality of projectiles, one each disposed in each of the plurality of cylindrical ports; a plurality of pressure seals, one each disposed in each of the plurality of cylindrical ports; and an end cap pressure seal capping off the end of the cylindrical thru hole where it terminates at an end of the second cylindrical housing, wherein energy source generates a gas at a pressure sufficient to propel the plurality of projectiles through the pressure seals and into a casing surrounding the perforating gun system.
 12. The perforating gun system of claim 11 wherein each of the plurality of cylindrical ports extend tangentially to the center axis of the second cylindrical housing.
 13. The perforating gun system of claim 11 wherein each of the plurality of cylindrical ports extend at a non-normal angle to the center axis of the second cylindrical housing.
 14. The perforating gun system of claim 11 wherein each of the plurality of cylindrical ports extend non-linearly from the center axis of the second cylindrical housing.
 15. The perforating gun system of claim 11 wherein the plurality of cylindrical ports has a phase angle between each cylindrical port about the center axis of the second cylindrical housing.
 16. The perforating gun system of claim 11 wherein the plurality of cylindrical ports are in a single phase.
 17. The perforating gun system of claim 11 wherein the plurality of cylindrical ports are in a single plane.
 18. The perforating gun system of claim 11 wherein the plurality of cylindrical ports are in a plurality of planes.
 19. The perforating gun system of claim 11 further comprising the first cylindrical housing has a pin end that engages into a box end of the second cylindrical housing.
 20. The perforating gun system of claim 11 further comprising the first cylindrical housing has an inner cavity that engages into a plug end of the second cylindrical housing. 